Intermediate telegraph station



1,655,420 J. HERMAN INTERMEDIATE TELEGRAPH STATION Filed April 17. 1926 Patented Jan.10, 1928.

, UNITED STATES TELEGRAPH COMPANY, A crearon-Arron or NEW YORK.

it INTERMEDIATE TELEGR'APH STATION.

PATENT OFFICE.

JOSEPH'HERMAN, 'OF NEIN YORK, AN. Y., ASSIG'NOR TO AMERICAN TELEPHONE AND Application inea April 17, 192e.` semaine.. 102,773.

This invention relates, to telegraph systems, and more particularly to improved arrangements for connecting telegraph suhscribers toone or more channels of acarrier telegraph system at intermediate points between the terminal stationsk of such Vsys-V tems. y The intermediate set of this `invention 1s particularly adapted for use with long can Yl() rier telegraph lines where a, small number of connections is required at some place near the middle of the lines. rangements of t-he `invention a number of the desired carrier channels maybe tapped at this intermediate point without providing terminal,repeaters thereat and the necessity of hack hauling theI signals from the distant terminals 'to the intermediate point may be doner away with. The intermediate set of the invention has-the further advantage that it does not require a local carrier generator and lthat variations in the adjustments of telegraph apparatus at the intermediate set will have littleor no effect upon through transmission. OtherV features'and purposes of the invention willappearmorefullyfrom the Vdetailed descriptionA thereof hereinafter givenLfmr y he invention-may be more fully understood from the following description t0- gether with the accompanying drawing, in the ligure of which is shown av circuit diagram of the intermediate set ofthe invention. Y In the drawing` are shown two lines intereonn'ecting distant stations, one line comyposed of the line sections .Lw and Le Vand the' other comprising4 theline sections Lw and Lc. These` lines mayv represent either two sides of a four-wire voice frequency tele/graph4 circuit, or the two transmission paths in opposite directions of atwo-.wire carrier telegraph repeater, kor twoy transmission paths in opposite directions with'two hands of frequencies located in different parts ofthe frequency spectrum in vthecase of high frequency kcarrier telegraph p circuits. cation of the invention which follows, however, will he coniinedto a four-wire voice frequency telegraph system, but it rwill be obvious that the arrangements .mayalso ap'- plyl to other types ofsystems suchas those heretofore mentioned. The intermediate set with these two limes nwill iVith the ar- The description of the specific appli? -tap any desired one of the telegraph channels transmitted thereover as will appear more fullyfrom lthe following detailed description of its operation. f I

The carrier currents which arrive atthe` intermediate station over the lines LwLe `and LwLe choose the following paths thereat: thoseV currents arriving over line :In/w, which it is not desired to tap andl for which `no intermediate set is provided, pass throughy the filter Fnetworlr VNmto line Le, and continue to the distant terminal station. Those currents for which an intermediate set is provided are prevented kfrom .passing Vthrough lter Fl because this filter dis-k criminates against them. rThese currents, therefore, choose one 'of the parallel paths around filter F1, as, for example, the path which consists of the filter F, network N2, armature and M contact ofy relay R2, filter F3, to line Le.v Similarly, currents arriving from line Le pass through identical circuit arrangements beforereaching line Lw. In 'orderto identify like elements in the two transmission paths, elementsin the` second path corresponding to those in the first path are designated-with the'same reference char acters, but with the addition of` the prime The above I, description has "served l to show how /the channels, into rwhich Vitis desired toconnectintermediate sets, may. he

separated from each other andv from those e channelson which such sets are .not desired. The method of receiving and transmitting onthese channels will nowbedescrihed.

lLet itbeassumed for, `purposes of illustration thatfit is rdesired*totap one `lof the lcarrier telegraph circuits, for which the two transmission channels in opposite directions areflocated in the Ytwo. transmission paths mentioned above. Let itrbe assumed further that the Aterminal `;sets for thisV particular n telegraph cii'cuitare arranged forhalfduplexoperation; and that the transmitting keys-on theseterminalisets are closed. Under'y theseconditions steadyxcarrier currents will Lbereceived ,from the linesaLw and Le foi: thetwo channels of this telegraph circuit.` The current 4for the channel v on line LwLfe willxpass through the `filter Fr2 and will divide between the detector D andthe network N?. Thecurrent which flows into network N2 `will passen throughy filter' lto' the. terminal set-s .connected `to line Liw, 'while that pommier ydie @einem which flows into the detector E will cause the armature of relay Rl to remain on its M contact. Similarly, the carrier cuirent from the line Lw of the channel under consideration passes through filter F, and divides between the detector D and network N2. Accordingly, one portion of this current passes on to the distant station connected to line Le, while the other portion'causes relay R, to rest on its M contacts. T the carrier current from line Lw for the channel under consideration is being interrupted in accordance with telegraph signals, then relay R1 will transmit telegraph signals into the differential loop circuit 5 and thereby operate the sounder 6 at the intermediate station. In a manner similar to the above, it will be apparent that it the signals were coming in over line Le instead of line Lw, then, relay RQ would be operatingv and transmitting signals into the diierential loop 5 and relay Rl would hold its armature on its M contact'.

The diterential loop circuit 5 utilized in the intermediate set ot this invention for half duplex telegraph service is operated alternately by two separate receiving relays, Rl andE R, in the manner described above. These relays are so arranged that either one may transmit a break signal rinto the loop, as will be pointed out hereinafter. The loop circuit 5 kcontains the windings voil three diterential polar relays, R3, R, and Rg.V These relays are unaffected by signals originating at relays R, or RQ, but

are` atlected by signals originating at key K. The normal condition of operation of the carrier circuit, when arranged for halfduplex oaeration, is such that the armature of one o the two relays Rl and Rl is resting on its M contact, while the other armature is transmitting signals into the loop. For this reason the armature ot' relay R', may be connected to the M contact of relay R1, in the manner shown on the drawing, with the result that either relay may transmit polar signals into the common apex of the loop circuit 5. Since spacing kbattery is connected to the S contacts ot' both relays, either relay may transmit a break signal inA order to interrupt transmission from the otherrelay or from the loop.

When transmitting 'from the intermediate station all. the other stations connected to the particular carrier channel under consideration will have, their transmitting keys closed. This is the normalV condition for half-duplex operation and will result in a steady carrier current being received at the intermediate station from the lines Lw and Le. If the key K at the intermediate station is then operated, relays R3, R2 and R2 will operate. This will result in the interruption ofthe steady carrier current by the armatures and contacts of relays' R2 and Ra.

when the intermediate station is sending.

This is due to the fact that the networks N2 and hl', re con ected into the circuit between the detectors and the points where 'the steady carrier currents are interrupted by the relays R2 and Rg, respectively. These networks are in thev nature ot artiiicial lines and present a fairly constant impedance to the inputoi the detectors, in spite ot the tact that the circuit is being opened and closed at their other ends.

` Considerabie attenuation may be experienced by the currents of those channels to which an intermediate station is connected due to the losses in the networks and filters through which they pass. For this reason an equal loss is introduced vby means ot networks N1 and Nl into those channels which pass through the filters F, and Fl, respectively, and to which an intermediate station is not connected. In order to make up for this loss it will be necessary to increase the gain of theV repeaters in the line, or, if this is not feasible, to connect an additional repeater into the line.

lVhenerer a terminal station wishes to interrupt the intermediate station, the transmitting key at the torinerstation isV opened. This interrupts the carrier current from that end ot the line and. effects one ot thev detectors and associated receiving relay7 at the intermediate station. is a resul@ spacing battery is connected to the apex oi the intermediate loop circuit 5, thereby interrupting the intermediate station. It the intermediate station wishes to interrupt a terminal' station while the latter is sending7 the key K atr the intermediate station is opened. This gives the operator at the intermediate station control of the cir'- cuit by virtue of the local break relay R3 and causes a cbreak signal to be transmitted to, the two terminal stations.

li it is desired to tap more than one carrier telegraph circuit at the intern'iediate station, other intermediate sets may bey con.- nected to the lines by conductors such as T' and S, T and S. n

For a inn-duinen circuit, two ditierential loop. circuits rwould be provided at the intermediate station. The break relay R, is then omitted and the relays R, and R2 are associated with one of' the two loop circuits and relays R', and R', with the other loopl The detailed circuit arrangements for such ay connection are weli known in the art and no further description thereof will be given.

-lll

VWhile the invention has `beenA`l v disclosed'as embodied in certain specic arrangements which are deeineddesirable, itis understoodV that it'is capable of.embodiinentfin many other and widely varied forms without departing 'from the spirit of the invention as delined in the appended claims. i

TWhat isl claimed is: `i

1. A four-wire transmission system'comprising two one-way line sections-for transmission in opposite directions, selective circuits connected to each ot said line sections, relay means in each of said selective circuits, and a local telegraph circuit jointly controlled by said relay means.

2. A carrier telegraph system comprising two one-way line sections for transmission in opposite directions, selective circuits connected in parallel with each of said line sections, relay means yin each of said selective circuits responsiye to the currents transmitted thereover, a local telegraph circuit controlled yby said relay means, and means in said local telegraph circuit yfor interrupting said select-ive circuits.

3.. A carrier telegraph systemcomprising two one-way line sections tor transmission in opposite directions, selective circuits connected inparallel with each of said line sections, relay means kin each of said selective circuits responsive to the currents trans.

mitted thereover, and a differential local telegraph circuit having its apex connected to said relays whereby said local circuit may be under the jointk control of said relays.

4. A carrier telegraph system comprising two one-way line sections for transmission in opposite directions, selective circuits connected in parallel with each et said line sections, detectors in "cachot said selective circuits, relay means associated with said detectors and `controlled by the currents transmitted over said selective circuits, a

local telegraph circuit controlled jointly by said relay means, and means 1n said local circuit for interrupting said selective circuits.

5. A four-wire transmission system comfl prising two one-way line sections for transmission inopposite d1rections,.seleetive circuits connected in series in each of said line sections, additional selective circuits connected in parallel with said series selective circuits, relay means in each ot said addi-A tional selective circuits, and a local telegraph circuit controlled by each oli-said relayV 6. A four-Wire transmission system comprising two one-way line sections for transmissiony in opposite directions, a combination of selective circuits connected into each ot said line sect-ions, relay means in certain ones ofsaid combination ot selective circuits, and local telegraph circuits controlled by said relay. means. v Y

7. A carrier telegraph systeml comprising two lone-Way `line sections- Vfor transmission transmitted thereover, a local telegraph crcuit controlled by said relay means, and means in saidlocal telegraph circuit or'in-A terrupting said selectivecircuits. v

8. A carrier telegraph system comprising two one-way line sections for transmission in opposite directions, a combination of selective circuits-connected into each Aof said line sections, relay means in certain ones of said combination et selective circuits responsive to the currentsk transmitted vthereover, local telegraph circuits controlled by said relay means, and means in said local telegraph circuits tor interrupting certain of saidselective circuits.

9. A carrier telegraph system comprising two one-Way line sections for transmission in opposite! directions, selective circuits connected in series in each of said line sections,

additional selective circuits connected in parallel with said series selective circuits, detectors in each of said additional selective circuits, relay means yassociated with said detectors and controlled by the currents transmitted over-said last mentioned selective` circuits, a local telegraph circuit controlled by saidk relay means, and means insaid local telegraph circuit for interrupting said `lastmentioned selectivecircuits. f

10. A carrier telegraph system comprising two one-way line sections for transmission in opposite directions, a combination of selective circuits connected into each of said line sections, detectors in certain ones of said combination ot selective circuits, relay means associated with said detectors and controlled by the currents transmitted vover said last mentioned selective circuits, local telegraph circuits controlled by said relay means, and means in ksaid local telegraph circuits for interrupting said last mentioned selective circuits.

ll. In a carrier telegraph system the combination With two one-way line sections for transmission lin opposite directions between terminal stations of an intermediate carrier telegraph station comprising a plurality ot selective circuits connected into each ot said line sections, detectors in certain members `of said pluralityk o' selective circuits, relay means associated with said detectors and controlled by currents transmitted from said terminal stations over said selective circuit members, local telegraph circuits controlled by said relay means, and means in said local circuits for interrupting said currents transmitted from said terminal stations.

12. In a carrier telegraph system, the comies 4: Lee-5,420

bination with t-Wo onefway line seotionsfor transmission in opposite directions between terminal stations, of an intermediate carrier telegraph station consisting or" a plurality -of selective circuits connected into each of said line sections, detectors in certain members of said plurality of selective circuits, relay means associated with said detectors and controlled by currents transmitted from said terminal stations over said selective circuit members7k local telegraph circuits conname toV this specification this 15th day of 20 April, 1926.

Y JOSEPH HERMAN. 

